Definitely cut out the caffeine in the late afternoon / evening. The rough guide I've heard is 6 hrs before you go to bed. No screen time before bed also helps -- it's got something to do with the blue light off the screen convincing your brain it's time to wake up. I also have a molded sleep mask that keeps it dark over my eyes as I fall asleep (I push it off during the night). The molding is important, so there's no pressure against your eyes. And if you develop the habit of lucid dreaming, you'll be certain that anything important you dream of will be remembered in the morning, which helps cut down the stress of frantically trying to remember words and phrases as you drift off to sleep.